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DefinitionGeochemical related hazards include arsenic, uranium (radon gas), manganese, and selenium. While these elements are naturally occurring, they can be detrimental to human health. It is possible that North Carolina could potentially experience any level of geochemical levels described for each of the elements described below. DescriptionArsenic
Radon Radon is derived from the radioactive decay of radium, and it is an extremely toxic, colorless gas. Radon can be found in the earth and rock beneath homes, in well water, and in building materials.xxvi Manganese Manganese is the twelfth most common element in the Earth's crust. It is found in soil, water, plants, and animals, as well as air particles. Everyday, people are exposed to manganese through their food, air, soil, and water. The United Sates National Academy of Sciences recommends manganese to be ingested at a level less than 11 mg daily. People living in an environment close to certain manganese using industries are at risk for a higher manganese exposure because of the airborne particles of the toxin. Although manganese is an essential micronutrient to humans, at high concentrations it is very toxic to humans and can cause many side effects including manganese poisoning and Parkinson's Disease. The manganese found in the human body is in the liver, bones, and kidneys.xxvii Selenium Selenium is a naturally occurring mineral element that is distributed widely in nature in most rocks and soils. In its pure form, it exists as metallic gray to black hexagonal crystals, but in nature it is usually combined with sulfide minerals or with silver, copper, lead, and nickel minerals. Selenium functions as an antioxidant and is needed for good health, but exposure to high levels can result in neurological effects and brittle hair and deformed nails. Occupational inhalation exposure may cause dizziness, fatigue, irritation of mucous membranes, and respiratory effects. This substance has been found in at least 494 of the 1,585 National Priorities List sites identified by the Environmental Protection Agency (EPA).xxviii Historical Occurrences Figure 3-10 displays the inflection points in stream sediment and groundwater for the geochemical related hazard elements.xxix Figure 3-10. Geochemical Inflection Point Measurements  Geochemical Related Hazard Scores Figure 3-11 represents the relative location of Geochemically-Related hazard vulnerability across the state of North Carolina. The vulnerability score for each county represents the scope, frequency, intensity, and destructive potential of this hazard and is an indication of future probability based on its relative score to other counties in the state. (The use of cooler colors—such as blues, purples, or greens—on the various hazard score maps presented in this section represents lower hazard vulnerability scores, while warmer colors—yellows, oranges, or reds—represent higher hazard vulnerability scores. This color scheme applies to this map and for comparisons to all of the other individual hazard maps.) Figure 3-11. Geochemical Related Hazard Scores by County 
Mine Collapse DefinitionSubsidence, in the context of underground mining, is the lowering of the Earth's surface due to collapse of bedrock and unconsolidated materials (sand, gravel, silt, and clay) into underground mined areas.xxx It is difficult to estimate the size of a mine collapse since many sites around the state are not well-documented and no major event has recently occurred in the state. Nevertheless, we estimate that a mine collapse could leave a pit several hundred squre feet in area with depths up to several hundred feet. Description There are two types of subsidence: (1) pit, also called sinkhole or pothole, and (2) sag or trough. (The term "sinkhole" more properly refers to solution collapse features in limestone.) Pit subsidence is characterized by an abrupt sinking of the surface, resulting in a circular steep-sided, craterlike feature that has an inward drainage pattern. It is associated with roof collapse of mines that have total overburden (overlying unconsolidated material and rock) of less than 165 feet, weak roof rock of shale or mudstone, and a ratio of unconsolidated-material thickness to rock thickness of less than 1.2. Pit subsidence does not occur where the thickness of the unconsolidated overburden is more than 90 feet. Sag subsidence is a gentle, gradual settling of the surface. It is associated with pillar crushing or pillar punching (discussed below) of deeper mines (overburden of more than 75 feet). Sag-subsidence features may fill with water if the surface of the subsidence intersects the water table. Pit-subsidence features generally do not hold water because the pit drains into the underlying mine.xxxi Figure 3-12 shows a diagrammatic cross section of typical subsidence resulting from mine-roof collapse. Figure 3-12. Diagrammatic Cross Section of Typical Subsidence Resulting From Mine-roof Collapse (no scale implied) 
Historical Impact Subsidence and collapse above abandoned underground mines occurs mainly in the rapidly urbanizing, old gold mining districts of the Piedmont. Accurately locating the mine workings is difficult, as most underground mining took place during the 18th and 19th centuries and reliable mine maps are rare.xxxii Through 2012 in North Carolina, there is no record in recent history of a mine collapse where human lives were lost. Mine Collapse Hazard Scores Figure 3-13 represents the relative location of Mine Collapse hazard vulnerability across the state of North Carolina. The vulnerability score for each county represents the scope, frequency, intensity, and destructive potential of this hazard and is an indication of future probability based on its relative score to other counties in the state. (The use of cooler colors—such as blues, purples, or greens—on the various hazard score maps presented in this section represents lower hazard vulnerability scores, while warmer colors—yellows, oranges, or reds—represent higher hazard vulnerability scores. This color scheme applies to this map and for comparisons to all of the other individual hazard maps.) Figure 3-13. Mine Collapse Hazard Scores by County 
Sinkholes Directory: div div -> 9th May 1950 the schuman declaration div -> Supplemental demographic information div -> Introduction A. Purpose & Authority div -> Executive summary 8 I. Introduction 26 II. State government capability 28 div -> General occupational safety and health rules subdivision z toxic and hazardous substances div -> Computer Basics What is a computer div -> Mobile county, alabama regular board meeting div -> Privacy: Campus Living & Technology Download 1.82 Mb. Share with your friends:
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